Two televisions with the same model number can perform differently. The cause is panel sourcing, and it is a normal feature of large-scale electronics manufacturing rather than a defect.
Panels come from several suppliers at once
Display panels are made by a small number of specialist manufacturers, and a television brand may not make its own at all.
To secure volume and manage price, a brand contracts with more than one panel supplier for the same product line, then fits whichever panels arrive at the assembly plant.
The finished sets are sold under one model number because the specification the brand publishes, such as size, resolution and refresh rate, is met by all of them.
The published specification does not capture the difference
Resolution and refresh rate are easy to state and identical across suppliers. Contrast behaviour, backlight uniformity and colour shift at an angle are harder to define and are usually not published at all.
Those unpublished characteristics are precisely where panel technologies diverge, and they are what a viewer actually perceives as picture quality.
So a set can match its advertised specification exactly while looking noticeably different from another unit of the same model in the next aisle.
Regional versions add another layer
The same marketing name is often applied to sets with different internal hardware in different regions, adapted for local broadcast standards and market positioning.
A review written for one market may therefore describe a product that is only loosely related to the one sold under that name elsewhere.
Model codes usually carry a regional suffix, and matching that suffix is the only reliable way to know a review applies to the set in front of you.
Production changes mid-cycle
Component sourcing can shift during a model's life as supply contracts change, so units built later in the run may differ from early ones.
Early reviews are typically written on launch units, which means the sample that shaped a product's reputation may not represent later production.
This is why owner reports spread over a longer period are more informative than a single expert assessment written at launch.
What a shopper can practically do
The variation is not large enough to make a well-reviewed model a bad choice, but it does mean expecting an exact match to a review is unrealistic.
Where picture quality matters, buying from a retailer with a straightforward returns policy converts an unknowable variable into a manageable one.
Judging a set on the qualities that do not vary, such as size, connections, software and support, leaves less riding on which panel happened to be fitted.